The present invention relates to methods and apparatus for treating lengths of timber in such a way that a length of timber which has a defect therein can be cut into a pair of pieces only one of which will have the defect.
The present invention relates in particular to methods and apparatus for determining a cutting line for such lengths of timber and for bringing this cutting line into alignment with a cutting means which will serve to cut the timber properly along the predetermined cutting line while the lengths of timber are continuously conveyed. Thus the present invention relates to a method and apparatus for longitudinally shifting lengths of timber transversely of their path of travel in order to properly determine where the lengths of timber will be cut so as to separate them into pieces for removing defects from the lengths of timber.
In order to save raw material, accurate sorting of lengths of timber has in recent times become the primary emphasis in the sawmill industry as well as other mechanical wood-refining industries. Subsequent to sawing and planing of timber, attempts are made to achieve the best possible quality of the timber by axially cutting away therefrom portions which have defects therein. Thus, by removing from a length of timber a portion thereof which has a defect therein, the remaining length of timber will have a higher quality and thus can command a higher price.
With the present-day development of timber-handling equipment, it is no longer possible or feasible to use workers to pull lengths of timber to cutting positions. The reason for this is that the work itself is extremely heavy and the sorting installations operate at a speed which is too great to enable such operations to be manually performed.
A common method utilized in cutting timber involves cutting the same into predetermined lengths so as to produce so-called module timber lengths. In this case, the method and apparatus of the present invention are utilized for cutting the timber at the region of one end therof, while the remainder of the timber is cut in the normal way to achieve the module-lengths thereof. At the present time, the cutting of timber into such module lengths is achieving greater importance. With the present invention it is possible to operate either on one or both ends of such lengths of timber in connection with the cutting thereof into suitable lengths.
With respect to the state of the prior art, reference may be made to Finnish Pat. Nos. 43,968 and 41,817, which illustrate features which can be utilized or applicable in connection with the method and apparatus of the present invention. Also, reference may be made to Finnish Pat. Nos. 44,046 and 49,586 both of which illustrate attempts to even up timber into specific dimensions.
According to Finnish Pat. No. 751,931, there is a disclosure enabling achievement of the same results which are achieved by way of the present invention. However, according to this patent it is necessary to utilize expensive and complex equipment and cutting operations must be carried out at two different places on a given length of timber, thus undesirably increasing the costs and the number of cut-off timber portions.